Attention deficit hyperactivity disorder (ADHD) is a developmental disorder characterized by inattentiveness, motor hyperactivity and impulsivity. According to neuroimaging data, the neural substrate underlying ADHD seems to involve fronto-striatal circuits and the cerebellum. However, there are important discrepancies between various studies, probably due to the use of different techniques. The aim of this study is to examine cerebral gray (GM) and white (WM) matter abnormalities in a group of ADHD children using a voxel-based morphometry protocol. The sample consisted of 25 children/adolescents with DSM-IV TR diagnosis of ADHD (medicated, aged 6-16 years) who were compared with 25 healthy volunteer children/adolescents. ADHD brains on an average showed a global volume decrease of 5.4% as compared to controls. Additionally, there were regionally specific effects in the left fronto-parietal areas (left motor, premotor and somatosensory cortex), left cingulate cortex (anterior/middle/posterior cingulate), parietal lobe (precuneus bilaterally), temporal cortices (right middle temporal gyrus, left parahippocampal gyrus), and the cerebellum (bilateral posterior). There were no differences in WM volume between ADHD children and control subjects. The results are consistent with previous studies that used different techniques, and may represent a possible neural basis for some of the motor and attentional deficits commonly found in ADHD.
"Previous functional neuroimaging studies have demonstrated dysfunctional neural activity of the motor cortex in ADHD children, such as reduced cortical activity and spatial extent of activation in the primary motor and parietal cortices (Mostofsky et al., 2006). Meanwhile, structural MRI studies in children with ADHD have reported atypical brain morphology in sensorimotor brain regions, such as gray matter (GM) volume decreases in the left precentral and postcentral areas (Carmona et al., 2005), and cortical thickness reductions of the precentral cortex (Shaw et al., 2006; Narr et al., 2009; Hoekzema et al., 2012). However, the morphological characteristics of the CS in children with ADHD and their relationships with the clinical symptoms have not yet been investigated. "
[Show abstract][Hide abstract] ABSTRACT: The central sulcus (CS) divides the primary motor and somatosensory areas, and its three-dimensional (3D) anatomy reveals the structural changes of the sensorimotor regions. Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder that is associated with sensorimotor and executive function deficits. However, it is largely unknown whether the morphology of the CS alters due to inappropriate development in the ADHD brain. Here, we employed the sulcus-based morphometry approach to investigate the 3D morphology of the CS in 42 children whose ages spanned from 8.8 to 13.5 years (21 with ADHD and 21 controls). After automatic labeling of each CS, we computed seven regional shape metrics for each CS, including the global average length, average depth, maximum depth, average span, surface area, average cortical thickness, and local sulcal profile. We found that the average depth and maximum depth of the left CS as well as the average cortical thickness of bilateral CS in the ADHD group were significantly larger than those in the healthy children. Moreover, significant between-group differences in the sulcal profile had been found in middle sections of the CSs bilaterally, and these changes were positively correlated with the hyperactivity-impulsivity scores in the children with ADHD. Altogether, our results provide evidence for the abnormity of the CS anatomical morphology in children with ADHD due to the structural changes in the motor cortex, which significantly contribute to the clinical symptomatology of the disorder.
Frontiers in Neuroanatomy 08/2015; 9. DOI:10.3389/fnana.2015.00114 · 3.54 Impact Factor
"These brain regions are known to mediate the cognitive control functions that are impaired in the disorder (Huizinga, Dolan, & van der Molen, 2006). Thus, reduced volume and cortical thickness have been observed in several frontal brain regions, in temporal-parietal areas, the basal ganglia, posterior cingulate, the cerebellum, and the splenium of the corpus callosum (Batty et al., 2010; Carmona et al., 2005, 2009; Castellanos et al., 2002; Mackie et al., 2007; Shaw et al., 2006). Despite the amount of working memory studies, EAM has been little examined in children with ADHD. "
[Show abstract][Hide abstract] ABSTRACT: Background Episodic autobiographical memory (EAM) has not been extensively investigated in children with attention-deficit/hyperactivity disorder (ADHD). The objective of this study was to examine EAM in school age children with ADHD in reference to the encoding period: recent memories (previous school years) and remote memories (first years of life).
Methods A sample of 29 children with ADHD and 29 typically developing children, matched for age and gender, completed a questionnaire to assess EAM. These participants were recruited from an initial sample of 572 participants. Developmental differences in accessing and recalling specific personal events and episodic details in groups with ADHD were predicted.
Results The control group showed a typical trend of EAM with fewer remote and episodic memories than recent ones. The ADHD groups showed a general EAM deficit. More precisely, the ADHD-I group performed equally poorly on remote and recent EAMs, whereas the ADHD-C group showed a higher number of remote EAMs than recent ones.
Conclusions The findings suggest that EAM can be impaired in children with ADHD. Clinical and medicolegal implications of these results and the relation between age and childhood amnesia are discussed.
"There are fewer known group level abnormalities in white matter as it is less frequently investigated using structural MRI [Hermann et al., 2007]. Although no differences in white matter volume were reported in one small study [Carmona et al., 2005], a larger study described significantly reduced total white matter volume and significant reductions in the frontal, parietal, temporal, and occipital lobes in ADHD [Castellanos et al., 2002]. Hermann et al.  reported a significantly decreased brainstem volume in patients with both ADHD and epilepsy compared with a healthy control group and a patient group with epilepsy alone compared with the control group. "
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